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Michał Strankowski, Łukasz Piszczyk, Paulina Kosmela and Piotr Korzeniewski

Abstract

In this study, thermally reduced graphene oxide (TRG)-containing polyurethane nanocomposites were obtained by the extrusion method. The content of TRG incorporated into polyurethane elastomer systems equaled 0.5, 1.0, 2.0 and 3.0 wt%. The morphology, static and dynamic mechanical properties, and thermal stability of the modified materials were investigated. The application of TRG resulted in a visible increase in material stiffness as confirmed by the measurements of complex compression modulus (E′) and glass transition temperature (Tg). The Tg increased with increasing content of nanofiller in the thermoplastic system. The addition of thermally reduced graphene oxide had a slight effect on thermal stability of the obtained materials. The incorporation of 0.5, 1.0, 2.0 and 3.0 wt% of TRG into a system resulted in increased char residues compared to unmodified PU elastomer. Also, this study demonstrated that after exceeding a specific amount of TRG, the physicomechanical properties of modified materials start to deteriorate.

Open access

Acta Botanica Croatica

The Journal of University of Zagreb

Open access

Journal for Technology of Plasticity

The Journal of University of Novi Sad

Open access

Mineralogia

The Journal of Mineralogical Society of Poland

Open access

South East European Journal of Economics and Business

The Journal of University of Sarajevo

Open access

M. Nabiałek

Abstract

This work presents studies concerning the relationship between reduction of glass transition temperature Trg and the glass-forming ability of FeCoB-based alloys. On the basis of theoretical considerations, Turnbull [1] determined the reduced glass transition temperature (Tg /Tl) as being 2/3 of the Vogel–Fulcher–Tammann (VFT) temperature; since then, continuous research has been carried out, aiming to calculate the Trg parameter and describe its relationship with glass-forming ability. In the majority of research papers, the reduced glass transition temperature is calculated from the relationship Tg /Tm, proposed by Uhlmann and Davies [2, 3]. On the basis of differential scanning calorimetry (DSC) studies, undertaken in this current work, the values of the following temperatures have been found: Tg, Tx, Tm and Tl, in addition to the temperature ranges: ΔTx, ΔTm and ΔTl. The correlation between: Tg/Tm, Tg/Tl and the glass-forming ability also has been discussed. Finally, for the investigated alloys, it has been found that the relationship proposed by Turnbull is reliable over a wide range of ΔTm.

Open access

J.J. Oak, Y.H. Kim, K.C. Bae and Y.H. Park

Abstract

The newly designed Ti-based bulk metallic glass (BMG) in which case of fracture behavior was observed 1990MPa to compressive strength with a wide plastic deformation around 7% after process of elastic deformation. This phenomenon can be compared with those of Ti-based alloys and other Ti-based BMGs and indicates high potential to be applied in use. It was evaluated the Ti-based BMG for thermal stability that the reduced glass parameters, ΔTx, Trg and γ, are 79K, 0.50 and 0.38, respectively. In addition, it reveals high activation energies for crystallization in which are estimated to E x1 = 291.77 ±9.71 kJ/mol, E x2 = 588.77 ±28.88 kJ/mol and E x3 = 330.26 ±3.61 kJ/mol on kissinger plotting in this study.

Open access

Štefan Bezek, Zuzana Brnoliaková, Ružena Sotníková, Vladimír Knezl, Ema Paulovičová, Jana Navarová and Viktor Bauer

Abstract

Elevated plasma cholesterol, especially low density lipoprotein (LDL) cholesterol, is one of the major risk factors for atherosclerosis and coronary heart disease. Hereditary hypertriglyceridemic rats (hHTG) were developed as a new inbred model for the study of relationships between blood pressure and metabolic abnormalities. The aim of this work was to determine the cholesterol-lowering and antioxidant effects of the novel pyridoindol derivative SMe1EC2, compared to the cholesterol-lowering drug atorvastatin, in rats fed either standard or high-fat and high-cholesterol diet (HFC; 1% cholesterol and 7.5% lard fat). Male hHTG rats fed HFC (HTG+HFC) were administered with SMe1EC2 or atorvastatin (both 50 mg/kg/day p.o.) for 4 weeks. Physiological status of animals was monitored by the measurement of preprandial glucose levels and blood pressure. Lipid profile was characterized by the serum levels of total cholesterol (TC), HDL-, LDL-cholesterol and triglycerides (TRG). The concentration of thiobarbituric acid reactive substances (TBARS) was evaluated in the kidney, liver and serum. Further, the assessment of pro-inflammatory cytokines TNF-α, IL-1 and IL-6 in the serum was completed. Feeding the animals with HFC diet resulted in increased serum levels of TC, LDL and TRG. SMe1EC2 ameliorated serum levels of LDL in hHTG rats, both on standard and HFC diet. These effects were comparable with those of the standard hypolipidemicum atorvastatin. SMe1EC2 lowered blood pressure, tissue TBARS concentrations and serum IL-1 levels of HTG+HFC rats. Beneficial effects together with very good toxicity profile predestinate SMe1EC2 to be promising agent for further surveys related to metabolic syndrome features.

Open access

Gordana Pejović and Jovan Filipović

Abstract

Background: Biosimilars are currently a reality of the pharmaceutical market in the European Union. This paper describes the current regulatory policy for approving biosimilars both in the European Union and in Serbia, which is not a Member State. Also, a comprehensive analysis on biosimilars consumption data on the Serbian market has been performed.

Methods: The European Medicines Agency has established a series of biosimilar scientific guidelines that comprises a regulatory policy for biosimilars in the European Union. This has enabled different biosimilar products to be marketed, making the European Union biosimilar market the most developed one globally. In the paper, this regulatory environment has been analysed, emphasising all relevant biosimilar guidelines as well as marketed biosimilar medicines. Also, an analysis is performed on Serbian regulatory requirements for approving and marketing biosimilars, analysing the Serbian regulatory authority’s consumption data as well as data available from the National Health Insurance Institution.

Results: In the paper, the comprehensive analysis of the current European Union as well as Serbian regulatory environment has been presented, with a special emphasis on the Serbian market potential for biosimilar medicines. Detailed consumption data has been analysed for the period 2007-2011.

Conclusion: Serbia has good potential for biosimilar products, which is supported by national health insurance policy and the general trend of cutting the reimbursement costs for prescription medicines. Five year consumption data for biosimilars in Serbia shows that the Serbian biosimilars market is very small in terms of market share values, especially comparing to other large European biosimilar markets.

Open access

Abdollah Alhevaz, Maryam Baghipur, Ebrahim Hashemi and Yaser Alizadeh

Abstract

Let G be a simple connected graph. The reciprocal transmission Tr′G(ν) of a vertex ν is defined as

TrG(ν)=uV(G)1dG(u,ν),uν.

The reciprocal distance signless Laplacian (briefly RDSL) matrix of a connected graph G is defined as RQ(G)= diag(Tr′ (G)) + RD(G), where RD(G) is the Harary matrix (reciprocal distance matrix) of G and diag(Tr′ (G)) is the diagonal matrix of the vertex reciprocal transmissions in G. In this paper, we investigate the RDSL spectrum of some classes of graphs that are arisen from graph operations such as cartesian product, extended double cover product and InduBala product. We introduce minimum covering reciprocal distance signless Laplacian matrix (or briey MCRDSL matrix) of G as the square matrix of order n, RQC(G) := (qi;j),

qij={1+Tr(νi)ifi=jandνiCTr(νi)ifi=jandνiC1d(νi,νj)otherwise

where C is a minimum vertex cover set of G. MCRDSL energy of a graph G is defined as sum of eigenvalues of RQC. Extremal graphs with respect to MCRDSL energy of graph are characterized. We also obtain some bounds on MCRDSL energy of a graph and MCRDSL spectral radius of 𝒢, which is the largest eigenvalue of the matrix RQC (G) of graphs.